Refrigeration systems such as air conditioning systems (A/C systems), e.g., in vehicles such as cars, buses or trucks, etc. contain a refrigerant which is added during the manufacture of the refrigeration system. When the refrigeration system is serviced and repaired there is a need to extract the refrigerant from the system and to refill refrigerant into the system afterwards.
Systems for filling refrigerant into refrigeration systems usually comprise a charging adapter and a charging valve for charging fluid refrigerant into the refrigeration system. Ideally the charging valve would be placed in the charging adapter so that the conduit connecting the internal refrigerant tank with the charging adapter would be filled with liquid refrigerant and the “dead volume” between the charging valve and the charging port would be very small.
The conduit being filled with liquid would make sure that the amount of refrigerant leaving the charging valve would be the same as the amount leaving a tank of the filling system, which can be measured with high accuracy by a weight-cell.
Having the “dead volume” very small would cause that the variation of the actual charging amount would be small and a high accuracy could be achieved when then system is filled with the refrigerant.
In conventional filling systems, however, the charging valve is usually placed inside the machine, which results in a distance of a couple of meters between the charging hose and the charging valve. As a result, variation of the ambient temperature will greatly effect if the charging line and the hose are filled with liquid or vaporized refrigerant. As a consequence, the amount of refrigerant filled into the refrigeration system may be determined only with reduced accuracy.